import java.util.Arrays;
import java.util.Scanner;

public class Test {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        StringBuilder str1 = new StringBuilder(in.nextLine());
        StringBuilder str2 = new StringBuilder(in.nextLine());
        for(int i = 0;i < str1.length();i++){
            for(int j = 0;j < str2.length();j++){
                if(str1.charAt(i) == str2.charAt(j)){
                    str1.deleteCharAt(i);
                }
            }
        }
        System.out.println(str1.toString());
    }
    public ListNode FindFirstCommonNode(ListNode pHead1, ListNode pHead2) {
        int len1 = listLength(pHead1);
        int len2 = listLength(pHead2);
        int diff = len1 - len2;
        ListNode p1 = pHead1;
        ListNode p2 = pHead2;
        if(len1 < len2){
            diff = -diff;
            p1 = pHead2;
            p2 = pHead1;
        }
        while(diff > 0){
            p1 = p1.next;
            diff--;
        }
        while(p1 != null && p2 != null){
            if(p1.val == p2.val){
                return p1;
            }else{
                p1 = p1.next;
                p2 = p2.next;
            }
        }
        return null;
    }

    public int listLength(ListNode head){
        int count = 0;
        ListNode cur = head;
        while(cur != null){
            count++;
            cur = cur.next;
        }
        return count;
    }
}
